For the purpose of safety, electronic products represented by mobile phones, computers, video cameras and electronic game machines, household and office electrical products represented by air conditioners, refrigerators, television images, audio products etc., and various products used in other areas require different degrees of flame retardancy.
In order to make the products achieve required flame retardant performance or grade, traditional techniques often utilize the following means: adding inorganic flame retardant materials such as types of metal hydroxides comprising crystal water, for example, aluminum hydroxide hydrate, magnesium hydroxide hydrate, and others, into a material system; and adding organic chemicals having a high content of bromine or halogen such as brominated bisphenol A, brominated bisphenol A epoxy resin and others into a material system. In order to improve the flame retardancy of these organic chemicals containing halogen, environmentally unfriendly inorganic chemical flame retardants such as antimony trioxide are often added into the system.
Due to the use of flame retardant materials containing halogen, it can produce toxic substances which cannot degrade or is difficult to degrade such as dioxin type organic halogen chemicals and others when burning, and those toxic substances pollute the environment and affect health of humans and animals.
For the purpose of protecting the environment, the flame retardant effect is achieved by using halogen-free compounds containing phosphorous and/or nitrogen and others as a flame retardant to replace halogen-containing compounds, especially in the electronic, electrical and electronic appliances industries, using reactive mono-functional (which means that there is only one active reactive group in one molecule) 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (hereinafter referred to as DOPO simply), more often derivatives of DOPO as a flame retardant component, with or without adding aluminum hydroxide hydrate and magnesium hydroxide hydrate.
In the electronic field, the reaction products (abbreviated as DOPO epoxy resin) of DOPO and high-cost, multifunctional epoxy resin, such as linear phenolic epoxy resin, o-methyl phenolic epoxy resin and bisphenol A phenolic epoxy resin are wisely applied as the epoxy resin material for copper-clad laminate use.
The copper-clad laminates produced by using DOPO epoxy resin have better flame retardancy. However, they have many defects in cohesiveness, heat-resistance and processability, and thus cannot meet the demand of high multilayer, high reliability, high cohesiveness and good processability for manufacturing modern communications. In addition, due to high cost, it is disadvantageous for them to spread to the civilian goods field such as consumer electronics demanding low-cost consumption, for example cell phones.
In the electronic field, DOPO reacts with such as, etherates of bisphenol A, bisphenol F, phenolic resin, phenol and o-cresol, to produce a phenol-containing compound containing DOPO skeleton (collectively called phosphorous-containing phenolic resin) which is used as a curing agent for epoxy resins or an additive for flame retardant materials, and as a flame retardant for epoxy resin materials for copper-clad laminate use.
The copper-clad laminates produced by using phosphorous-containing phenolic aldehyde as a part of or all of the flame retardant ingredients can achieve flame retardancy. However, there are many defects in acid/base resistance, chemical resistance, cohesiveness, heat resistance, processability and so on, so that they cannot meet the demand of high multilayer, high reliability, high cohesiveness and good processability for manufacturing modern communications. In addition, due to high cost, it is disadvantageous for them to spread to the civilian goods field such as consumer electronics demanding low-cost consumption, for example cell phones.
With the factors such as improvement of the electronic industry towards demands of short, small, thin, high multilayer and high reliability, and popularization of civilian consumer electronics, and pressure of more serious environmental pollution, there is an urgent market demand for cheap flame retardant substances having good flame retardancy, heat resistance and good mechanical properties.